Today is a hot, humid day. The outside temperature is 34.0c, and the relative humidity is 85.0% however. Your cars air conditioning system maintains a comfortable 22.0C while you drive. The system draws in air from outside and mixes it with a recycle stream of air from inside the car. The mixed air then gets sent to then air conditioner, where it is cooled to 19.0 C and delivered to the car at rate of 15.0(m*3/hour). A pure liquid stream of water leaves the bottom of the air conditioner. Assume that the entire system runs at atmosphere pressure and that the air in stream 2 is saturated. a) a. calculate the molar flow rate of stream 2 in [mol/hr]. b) b. calculate the molar composition of streams 1 and 2 [mol/hr]. c) c. calculate the molar flow rate of stream 1 [mol/hr]. d) d. calculate the rate of condensation of water from the air conditionermol H20/ mol] e) eif the temperature of stream 5 (is 25.0, write the following equations, which will allow for the solution of the molar flow rate of stream 4. i. write a total material balance around the mixer. ii. Write a material balance for water around the mixer. ii. Using heat capacities, write an energy balance around the mixer. iv. Write expression for the heat capacities of stream 1, 4, and 5. Explicitly solve for the heat capacities of stream 1 and 4 assuming that the heat capacity of water is 3.36E-2 kj/(mol), and the heat capacity of the dry air is 2.91E-2 kJ/(mol). Recall that an equation exists to estimate the heat capacity for the mixture. v. Write the conservation of probability equation for the stream 5. [Hint: the functional composition of the components in this stream should add to .vi. For all the equation in part i,-v., identify the unknown in the equation and perform a degree of freedom analysis on the system. vii. If your equation are correct, they can be used to find a molar flow rate in stream 4 of 973 mol/hr. discuss the molar flow rate of stream 4 compared to that of stream2. f) Find the composition of steam 5 using the equations that you wrote above. Note: not all of the equations will be needed. G) Find the vapor pressure of water (p*) in steam 5 using Antoine\'s equations. h) Find the relative humidity of stream 5 using the definitions of relative humidity and partial pressure. I) Using the equations in part e, derive a closed form solution for the molar flow rate stream 4, and confirm the value given in part vii
But all\'s not lost! Instead of letting the power of science defeat us, we just have to use it the right way.
Suppose you take a refrigerator and build your house around it, so half the machine (the chiller cabinet) is inside your home and the other half (the grid of hot fins at the back) is outside. Now if you leave the door open, what you have in effect is a fully fledged air conditioner. It draws in heat from inside your home and belches it out again outside, gradually cooling your home in the process.
The simplest air conditioner units work in almost exactly this way, except they have fans on both sides to circulate air more rapidly. They also have a heating element in them so they can warm the air in a room on cold days as well as cool it down on warm days. Machines like this are sometimes called HVACs (heating and ventilation air conditioning units). More elaborate air conditioners use long ducts to pipe the warmed or cooled air throughout an entire building, but they still work in essentially the same way.
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